1. Field of the Invention
The present invention relates to a liquid crystal panel with a color filter and a liquid crystal display device.
2. Description of the Related Art
In recent years, a liquid crystal display device has widely been used for monitors of a notebook computer and a television set, and the like. In particular, the use of a liquid crystal display device for a large-sized television set has rapidly been expanded.
On the occasion of viewing a liquid crystal display device from an oblique direction, high contrast ratio thereof is highly valued. In particular, the improvement of viewing angle properties is an important problem in a liquid crystal display device in color display.
Contrast ratio is used as one of indicators for evaluating performances of a liquid crystal display device. The contrast ratio is represented by the ratio between luminance in displaying white (white luminance) and luminance in displaying black (black luminance). Accordingly, higher white luminance and lower black luminance allow a liquid crystal display device having a higher contrast ratio. A liquid crystal display device having a high contrast ratio brings definite difference between white and black to allow favorable image display to be realized.
Incidentally, a liquid crystal layer into which a liquid crystal material is injected causes light leakage in the case of viewing from an oblique direction by reason of having birefringence (retardation) in itself. The light leakage causes contrast ratio to decrease in a liquid crystal display device. Then, in order to improve viewing angle properties of a liquid crystal display device, an optical compensating layer (also referred to as a compensating plate, a retardation plate and a viewing angle widening film) has conventionally been disposed in a liquid crystal cell. However, with regard to a liquid crystal panel with a color filter, light which passed through a liquid crystal layer and the color filter enters human eyes. Accordingly, it is necessary that the compensation including retardation in the thickness direction of a color filter as well as a liquid crystal layer be performed for the liquid crystal cell.
A liquid crystal display device is known, in which a retardation layer corresponding to each color region of a color filter is provided between two substrates as the compensation in consideration of the color filter (Japanese Unexamined Patent Publication No. 2002-122866). However, in this means, it is required that a retardation layer having a different retardation value be provided in each color region of a color filter.